A big country of aerospace with black technology

The new 110-ton liquid oxygen kerosene engine has been tested dozens of times on the test bench in the last six months, with a combined duration of more than 10,000 seconds.

Multiple rounds of tests have been carried out on the running state of the new liquid oxygen kerosene engine under various working conditions, and detailed data of the engine under different conditions such as ground environment and high-altitude environment have been obtained.

The high-altitude environment and the ground environment have a relatively large impact on the engine. The low gravity at high altitude, thin atmosphere and low temperature all have a certain impact on the operation of the engine.

This means that the rocket engine has its own oxidant, and it is replaced by an aircraft engine that uses air as the combustion oxidant, which has long been useless in a high-altitude environment.

In the past six months, the test run time of a single engine has also increased from more than 400 seconds to more than 1,000 seconds.

Because the new liquid oxygen kerosene engine is likely to be used on the first batch of recoverable rockets that will be tested next year, the service life of the engine is directly related to the number of times the rocket is used.

Every extension of the service life of the rocket engine basically means that a part of the cost of using the recoverable rocket will be reduced.

Only when the cost of using recoverable rockets is low enough, can Zhang Xingyang be sure to persuade the leaders above to carry out the seemingly exaggerated low-orbit satellite communication network plan.

After all, according to Zhang Xingyang's description, the number of satellites in the entire plan has reached an incredible 50,000 or more, and the number of satellites that need to be replaced every year has reached about 20,000.

Even if the thrust of the rocket newly developed by the Rocket Research Institute is strong enough, hundreds of low-orbit communication satellites can be launched in each launch.

This still requires more than 500 rockets, and the cost of the rocket alone is billions, close to tens of billions.

This is just the cost of building this satellite communication network, not counting the annual maintenance cost behind it.

Annual maintenance needs to launch more than 20,000 satellites. If the traditional one-time rocket solution is adopted, more than 200 rockets are needed. Even if the domestic price is not very high at this time, the cost of labor and materials is very low, and the cost is close to Three or four billion.

You need to know how much the annual military expenditure is, which is less than 50 billion in total.

This will also be distributed to the army, navy and air force, and the Second Artillery Force (later the Rocket Army) that exists as a strategic deterrent.

And if the strategy of rocket recovery is adopted, even if the first batch of rockets cannot achieve the theoretical ten recovery times due to technical problems, and only three or four times of reuse can save close to 60% rocket cost.

In other words, the construction cost of the entire system can be reduced from the original tens of billions to three to four billions, and the subsequent maintenance costs are only about two billions per year.

And this is only the cost of a complete set of low-orbit satellite communication network.

According to Zhang Xingyang's idea, within the first two years, basically only the domestic communication network can be completed.

If the domestic communication network is to be successfully constructed, only 4,000 low-orbit satellites are needed to complete the basic construction.

Moreover, these 4,000 satellites can still be completed in stages. According to Zhang Xingyang's plan, the first phase of the construction project can be completed with only 1,000 satellites.

After all, what everyone needs most at this time is not the high-speed Internet access function like later generations. For many people who have never even touched a mobile phone in their life, the voice call function is the highlight.

The amount of data transmission occupied by the voice call function is completely incomparable with the Internet function.

Because the first few rockets will not directly use second-hand, third-hand or even nine-hand rockets, the cost will be slightly higher.

But this is also necessary, because the first few launches must test the rocket's performance to some extent.

In order to allow the recoverable rocket to catch up with the first experimental launch within 97 years, the people of each system are desperately trying to catch up with the progress.

The most critical and difficult part of the entire system is the propulsion system of the first-stage rocket.

The first-stage rocket propulsion system using eleven YF-110 liquid oxygen kerosene engines, in the eyes of rocket engineers in this era, is basically a monster-level difficulty.

You know, no one in China has ever done such a complex propulsion system before.

Because this rocket only has a two-stage structure, the first-stage rocket as the main source of propulsion is extremely demanding, and the three-stage rocket system was generally used in China before.

Compared with the two-stage rocket structure, the three-stage rocket system has stronger redundancy capabilities, and can more easily adjust the attitude of the rocket during flight.

However, the overall structure of the three-stage rocket will be relatively more complicated, but the propulsion system of each stage will be simpler. After all, each stage needs to be propelled to a lower height.

Especially for the rockets commonly used at this time, there have never been so many rocket engines per stage.

Take the Changsanyi rocket launched not long ago as an example. Its first-stage rocket uses four YF-31C liquid rocket engines.

Although four boosters using YF-25 rocket engines were used at the same time, it was actually less difficult because of the bundled form used.

After all, when the Changsanyi rocket was launched, the four YF-21C liquid engines and four boosters of the first-stage rocket were ignited at the same time.

As for the eleven rocket engines of the newly developed recoverable rocket, because the recovery function must be considered, some of the rocket engines must be turned on during recovery, so that the first-stage rocket can decelerate and land.

This requires that the eleven engines of the new recoverable rocket can be controlled separately and ignited in batches.

This puts forward higher requirements for the design difficulty of the entire first-stage rocket propulsion system. Compared with the difficulty of previous rocket design, one seems to be climbing Mount Tai, while the other is climbing Mount Everest.

It is precisely because of this that Zhang Xingyang arranged this multi-rocket engine linkage test to test the mutual influence of the engines when they are running separately.

The number of engine linkages tested has been increased from two to eleven, in order to gradually explore the influence between them.

This is also to prepare for the launch of various models with different thrust levels and different orbital carrying capacities in the future.

After all, it is impossible to use high-thrust rockets every time. Sometimes in some commercial launch missions, some low-thrust, low-cost rockets are also needed.

For example, there are only four YF-110 liquid rocket engines used as a small-thrust rocket for the first-stage rocket propulsion system, and the entire cost is only about five million, which is very suitable for commercial launch missions of some small satellites.